1. Field of the Invention
The invention relates to a power supplying device, more particularly to a portable power supplying device.
2. Description of the Related Art
As shown in FIG. 1, U.S. Patent Application Publication No. 2005/0231155A1, entitled “Battery Pack with Power Input/Output”, discloses a battery pack 1 including a base 11, a cover 12 coupled removably to the base 11, a battery terminal unit 13, an output terminal 14 provided on one side of the base 11, an input terminal 15 provided on the side of the base 11 and adapted to connect to a commercial AC power source, and a switch control member 16 provided on the side of the base 11 and connected electrically to the output and input terminals 14, 15.
The base 11 is formed with two battery mounts 111 spaced apart from each other, and adapted to receive battery members 17 therein, respectively. The battery terminal unit 13 includes a positive/negative terminal 131, a negative terminal 133, and a positive terminal 132 that are mounted respectively to the battery mounts 111. The positive/negative terminal 131, the negative terminal 133, and the positive terminal 132 can be connected such that the battery members 17 received in the battery mounts 111 are connected in series, or can be connected such that the battery members 17 received in the battery mounts 111 are connected in parallel.
The switch control member 16 is operable in a selected one of a first power supplying state, where the switch control member 16 breaks electrical connection between the battery terminal unit 13 and the input unit 15, and makes electrical connection between the battery terminal unit 13 and the output terminal 14, such that the battery members 17 are able to supply power to an electrical device connected to the battery pack 1 via the output terminal 14, and a charging state, where the switch control member 16 breaks electrical connection between the battery terminal unit 13 and the output unit 14, and makes electrical connection between the battery terminal unit 13 and the input terminal 15, such that the battery members 17 are charged by the commercial AC power source via the input terminal 15.
In addition, the switch control member 16 is further operable in a second power supplying state when no battery members are received in the battery mounts 111, where the switch control member 16 makes electrical connection between the input and output terminals 15, 14 such that power is supplied to an electrical device via the output terminal 14 by the commercial AC power source that is connected to the input terminal 15.
Although the battery pack 1 can be used both as a power supplying device and as a charger, the battery pack 1 still has the following shortcomings:
1. The battery pack 1 is limited in that the output voltage cannot be adjusted according to different kinds of batteries, thereby making the battery pack 1 inconvenient to use:
Since the battery terminal unit 13 is provided such that the battery members 17 received in the battery mounts 111 are connected in a single fixed arrangement, i.e., either in series or in parallel, only batteries with specific voltage output levels can be used for the battery pack 1. In other words, the battery pack 1 is not suitable for a range of batteries with varying specifications, and is not adjustable for application to devices with different output voltage requirements.
2. The battery pack 1 is not suitable for outdoor use:
The battery pack 1 can only use the commercial AC power as its source for charging the battery members 17. If the battery members 17 are out of power when the battery pack 1 is at a location where commercial AC power is not available, then the battery pack 1 would become useless, i.e., can neither supply power to electronic devices nor charge battery members 17. Consequently, although the battery pack 1 is suitable for indoor use, it is relatively unsuitable for outdoor use.